This is a running count of bytes, rather than packets, transmitted out through this specific adjacency. Byte counts per adjacency let an admin estimate actual bandwidth utilization toward a specific neighbor, which is what actually matters for capacity planning on a shared-media segment where multiple adjacencies compete for the same physical link bandwidth. Comparing this counter across the three neighbor adjacencies on a shared LAN segment could reveal that one neighbor is consuming 80 percent of the link's outbound bandwidth, guiding where to focus a congestion investigation.